Glow-in-the-dark

The low-level radioactivity of tritium can be converted into fluorescent light energy ("litroenergy") by bringing it into contact with phosphorus.  By encapsulating both components inside microspheres, a Wisconsin company is developing glow-in-the-dark paints. 

The MPK packaging of tritium into microspheres that have a 5,000-pound crush resistance, makes this technology safe. In the case of release into the air, it essentially is released as hydrogen. The "soft" radioactive emissions from the tritium do not penetrate through the walls of the microsphere encapsulation... The cost to light up 8½ x 11 piece of plastic... with Litrospheres is about 35 cents.

Another company is using similar technology to produce luminescent lighting strips:

The Lunabright products activate after a few minutes' exposure to daylight or artificial light, then continue to glow for several hours.  The presumed use would be for safety- and security-related applications.

I'm not pimping either of the products or the companies - just thought the new technologies are kind of cool.